Some believe that reinforced concrete and concrete structures are the most reliable. But this belief is erroneous. Such structures are subject to destruction and damage when exposed to certain factors. This can be affected by frost, groundwater, soil deformation, rain and chemicals. Salvation in this situation is sulfate-resistant cement. It is popular in countries where the weather dictates its laws to builders.
Cooking
This type of cement is obtained from crushed clinker, which is mixed with calcium and silicate aluminate. Particular attention is paid to the dosage. Aluminate, for example, should not be contained in a volume of more than 5%, as for silicate, its volume is 50%. This ratio is not random. In nature, there are many sulfates, which, in contact with tricalcium hydroaluminate, cause sulfate corrosion. The feedstock contains a minimum amount of iron.
Application
Sulphate-resistant cement is used for concreting underground and underwater arrays. It has unique properties, therefore, it is resistant to external chemical and natural factors. This cement is immune to aggressive chemicals that are indispensable in construction.
In those conditions where ordinary building materials are not able to create a strong structure, the described cement helps. It has a low degree of hardening, which distinguishes it from ordinary cement. Density is the main factor that determines the durability of the work performed.
State standards. Varieties. Composition
Sulfate-resistant Portland cement can have a different composition and can be:
- Portland cement slag;
- with mineral additives;
- pozzolanic Portland cement.
This building material is resistant to factors of chemical and natural origin. The composition contains components that allow you to get a building that is not subject to destruction due to variable temperature and moisture.
When choosing a sulfate-resistant Portland cement, you need to familiarize yourself with the composition, because for a certain soil a certain material is needed. The described is based on clinker, silicate and calcium aluminate. It is widely used in the construction of hydraulic structures. Such cements are made in accordance with GOST 22266-2013.
Characteristics SSPTS 400-D0
Sulfate-resistant cement SSPTS 400 DO is a type of Portland cement. It is resistant to sulfate water. Even ordinary groundwater contains a large amount of sulfates. They contribute to the destruction of concrete. To protect structures made of concrete from sulfate aggression, SSCS is used.
Cement is widely used in the construction of foundations, bridge supports with a high level of groundwater. Along with certain advantages, this type of Portland cement has all the main characteristics of the PC 400-D0. The compressive strength mark is mentioned in the marking and is 400 on the 28th day. Hardening speed is normally hardening. This material is made in accordance with GOST 22266-94. The compressive strength on the third day is not standardized. At the age of 28 days, the compressive strength is 39.2 MPa. The tensile strength on bending on the 28th day is 5.4 MPa. Gripping starts at the 45th minute, not earlier. There are no mineral additives in this cement.
Cement additives
The described product is obtained by grinding clinker of normalized mineralogical composition and gypsum. On sale you can find Portland cement with mineral additives in the form of electrothermophosphate slag and granulated blast furnace slag. These substances are added in a volume of 20% of the total mass. Active additives may be in the range of 5 to 10%. Such cement, GOST of which was mentioned above, has a relatively low alumina module, as well as a saturation coefficient.
For the manufacture of clinker, in which not more than 5% SzA and not more than 50% C3S. The total amount of C3A and C4AF should not be more than 22%. Additives for cement are C3A and C3S. In this regard, the material has reduced heat, since the substances mentioned are contained in moderation. On sale you can find a sulfate-resistant variety with a marking of 400. If there are mineral additives, then the brand can be 500. The compressive strength on the 28th day is 40 MPa, if there are mineral additives, this figure rises to 50 MPa.
This material is used to create concrete structures, hydraulic structures, exposed to sulfate-containing water.
Labeling Explanation
Building cements have their own marking, approved and described in SNiLS and GOST. Material can be produced according to other regulatory documents. If you saw the PC among the first letter designations, then Portland cement is in front of you. Slag Portland cement is indicated by the abbreviation ShPC. Understand that you have a sulfate-resistant Portland cement in front of you, you can spell the TWS or SSPTs.
When mineral additives are present in the material, the letter D is added to the abbreviation, then the marking is as follows: SPDC. Sulphate-resistant slag Portland cement is indicated by the marking SSCHPC. If you have pozzolanic and tensile cements, you will see the following letters: PPC and SC, respectively. White Portland cement and waterproof expanding cements are indicated by the letters PCB and VRC.
Cement labeling and decoding is important to the consumer. So he will be able to purchase the goods he needs. After the first letters, numbers will be indicated, which in the marking are as follows: PC-500. This indicates that you have 500 grade cement. Other numbers and letters may follow the marking. For example, if there is a maximum content of additives in cement, then you will see: D0, D5, D20. This corresponds to a percentage ratio of 0.5 or 20%.
Fast-hardening cement is indicated by the letter B. Plasticizing cement is a submarine, hydrophobized cement - GF. The material with the normalized composition of clinker is N. At the end of the labeling, the normative document is indicated. These may be technical specifications or state standards on the basis of which the material is manufactured.
Plasticized and hydrophobic Portland cement
Plasticized Portland cement differs from the usual ability to give concrete and mortar increased mobility. This effect can be achieved by introducing clinker in the amount of 0.25%. The hydrophobic additive is sulfide-yeast mash. It increases the plasticity of the cement paste. Concrete structures with the addition of such cement receive a plasticizing effect, which allows to reduce the water-cement ratio and increase the density, as well as the water resistance of the structure.
Hydrophobic Portland cement is made with the introduction of clinker in a volume of 0.1%, asidol, as well as synthetic fatty acids. The composition may also include hydrophobizing additives. These substances are able to reduce hygroscopicity, so cement differs from normal in that it does not deteriorate when stored in wet conditions. He does not crumple and remains active. In this regard, sulfate-resistant Portland cement of a hydrophobic type is recommended for use in areas with high humidity. The main substance is stored there in hardened materials and increases their water resistance, increasing resistance to external aggressive conditions.
Sulphate Resistant Concrete
Today, such concrete can be obtained in two ways. The first is to add cement with special modifying agents. The 2nd technology is expressed in the preparation of a solution using sulfate-resistant cement. This technique is more preferable and reliable. After all, the cement described above, the GOST of which was mentioned in the article, is able to protect the material at all stages of the construction life.
Concrete made by the first technology will also be protected from negative factors, but such protection can be compared with the treatment of shoes with a water-repellent composition. As for the sulfate-resistant solution, it is an analogue of rubber boots. The difference is significant. Among other things, there is still a gradation in compression strength on the 28th day.
Finally
Sulphate-resistant Portland cement is a type of regular Portland cement. It is resistant to sulfate water. Indeed, even ordinary groundwater contains a huge amount of sulfates. They ultimately contribute to the destruction of concrete.
In order to effectively protect concrete structures from such influences, special-purpose cement is used. Today it has found its wide distribution in the construction of foundations and supports of bridges, which are operated at a high level of groundwater.
One of its additional advantages can be considered that its storage is permissible in more difficult conditions. This applies, for example, to high humidity, at which clumping and caking does not occur over time.